ASTM E1445-08(2015)
(Terminology)Standard Terminology Relating to Hazard Potential of Chemicals
Standard Terminology Relating to Hazard Potential of Chemicals
SCOPE
1.1 This standard is a compilation of terminology used in the area of hazard potential of chemicals. Terms that are generally understood or adequately defined in other readily available sources are not included.
1.2 Although some of these definitions are general in nature, many must be used in the context of the standards in which they appear. The pertinent standard number is given in parentheses after the definition.
1.3 In the interest of common understanding and standardization, consistent word usage is encouraged to help eliminate the major barrier to effective technical communication.
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1445 − 08 (Reapproved 2015)
Standard Terminology Relating to
Hazard Potential of Chemicals
This standard is issued under the fixed designation E1445; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E698Test Method for Arrhenius Kinetic Constants for
Thermally Unstable Materials Using Differential Scan-
1.1 This standard is a compilation of terminology used in
ning Calorimetry and the Flynn/Wall/Ozawa Method
the area of hazard potential of chemicals. Terms that are
E771Test Method for Spontaneous Heating Tendency of
generally understood or adequately defined in other readily
Materials (Withdrawn 2001)
available sources are not included.
E918Practice for Determining Limits of Flammability of
1.2 Althoughsomeofthesedefinitionsaregeneralinnature,
Chemicals at Elevated Temperature and Pressure
many must be used in the context of the standards in which
E1226Test Method for Explosibility of Dust Clouds
they appear. The pertinent standard number is given in paren-
E1231Practice for Calculation of Hazard Potential Figures-
theses after the definition.
of-Merit for Thermally Unstable Materials
1.3 In the interest of common understanding and
E1232Test Method for Temperature Limit of Flammability
standardization, consistent word usage is encouraged to help
of Chemicals
eliminate the major barrier to effective technical communica-
E1491Test Method for MinimumAutoignitionTemperature
tion.
of Dust Clouds
E1515Test Method for Minimum Explosible Concentration
2. Referenced Documents
of Combustible Dusts
E1981Guide for Assessing Thermal Stability of Materials
2.1 ASTM Standards:
by Methods of Accelerating Rate Calorimetry
E476Test Method for Thermal Instability of Confined Con-
E2012Guide for the Preparation of a Binary Chemical
densed Phase Systems (Confinement Test) (Withdrawn
Compatibility Chart
2008)
E2019Test Method for Minimum Ignition Energy of a Dust
E487Test Method for Constant-Temperature Stability of
Cloud in Air
Chemical Materials
E2021TestMethodforHot-SurfaceIgnitionTemperatureof
E537Test Method for The Thermal Stability of Chemicals
Dust Layers
by Differential Scanning Calorimetry
E2046TestMethodforReactionInductionTimebyThermal
E582 Test Method for Minimum Ignition Energy and
Analysis
Quenching Distance in Gaseous Mixtures
E659Test Method for Autoignition Temperature of Liquid
3. Terminology
Chemicals
E680Test Method for Drop Weight Impact Sensitivity of
3.1 Definitions:
Solid-Phase Hazardous Materials
adiabatic calorimeter, n—an instrument capable of making
E681TestMethodforConcentrationLimitsofFlammability
calorimetric measurements while maintaining a minimal
of Chemicals (Vapors and Gases)
heat loss or gain between the sample and its environment,
whichisverifiablebythecapabilitytocontinuouslymeasure
the temperature differential between the sample and its
ThisterminologyisunderthejurisdictionofASTMCommitteeE27onHazard
surroundings. E1981
Potential of Chemicals and is the direct responsibility of Subcommittee E27.01 on
Editorial and Nomenclature.
adiabatic decomposition temperature rise, (T) , n—an esti-
d
Current edition approved Feb. 1, 2015. Published April 2015. Originally
mation of the computed temperature which a specimen
approved in 1991. Last previous edition approved in 2008 as E1445–08. DOI:
10.1520/E1445-08R15. would attain if all of the enthalpy (heat) of decomposition
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
reaction were to be absorbed by the sample itself. High
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
values represent high hazard potential. E1231
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
anvil, n—the smooth, hardened surface upon which the test
The last approved version of this historical standard is referenced on
www.astm.org. sample or cup containing the sample rests. E680
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1445 − 08 (2015)
−E/RT
Arrhenius equation—k= Ze where k is the specific
t = time, (s),
reaction rate constant in reciprocal minutes for first order, Z
V = volume, (m ), and
is the pre-exponential factor in reciprocal minutes, E is the
K = (bar m/s).
St
Arrhenius activation energy in J/mol, R is the gas constant,
E1226
8.32 J/mol K, and T is the temperature in kelvin. E698
differential scanning calorimetry (DSC), n—a technique in
autoignition, n—the ignition of a material commonly in air as
which the difference in energy inputs into a substance and a
the result of heat liberation due to an exothermic oxidation
reference material is measured as a function of temperature,
reactionintheabsenceofanexternalignitionsourcesuchas
while the substance and the reference material are subjected
a spark or flame. E659
to a controlled temperature program. E698
DISCUSSION—Two modes, power compensation differential scanning
autoignition temperature, n—the minimum temperature at
calorimetry (power compensation DSC) and heatflux differential scan-
which autoignition occurs under the specified conditions of
ningcalorimetry(heatfluxDSC),canbedistinguisheddependingonthe
test. E659
method of measurement used.
DISCUSSION—Autoignition temperature is also referred to as sponta-
differential thermal analysis (DTA), n—a technique in which
neous ignition temperature, self-ignition temperature, autogenous igni-
tion temperature, and by the acronymsAIT and SIT.AIT is the lowest the temperature difference between a substance and refer-
temperature at which the substance will produce hot-flame ignition in
encematerialismeasuredasafunctionoftemperaturewhile
airatatmosphericpressurewithouttheaidofanexternalenergysource
the substance and the reference material are subjected to a
such as spark or flame. It is the lowest temperature to which a
controlled temperature program. E698
combustible mixture must be raised, so that the rate of heat evolved by
the exothermic oxidation reaction will over-balance the rate at which
(dP/dt) , n—the maximum rate of pressure rise during the
ex
heat is lost to the surroundings and cause ignition.
course of a single deflagration. E1226
compatibility, adj—the ability of materials to exist in contact
(dP/dt) , n—maximum value for the rate of pressure in-
max
without specified (usually hazardous) consequences under a
crease per unit time reached during the course of a defla-
defined scenario. E2012
grationfortheoptimumconcentrationofthedusttested.Itis
determined by a series of tests over a large range of
constant-temperature stability (CTS) value, n—the maxi-
concentrations. It is reported in bar/s. E1226
mumtemperatureatwhichachemicalcompoundormixture
may be held for a 2-h period under the conditions of the test
drop weight, n—that weight which is raised to a selected
without exhibiting a measurable exothermic reaction. E487
height and released.This weight does not impact the sample
cool-flame, n—a faint, pale blue luminescence or flame occur- directly; rather it strikes another stationary weight that is in
contact with the sample. E680
ring below the autoignition temperature (AIT). E659
DISCUSSION—Cool-flames occur in rich vapor-air mixtures of most
DTA (DSC) curve,n—arecordofathermalanalysiswherethe
hydrocarbons and oxygenated hydrocarbons. They are the first part of
temperature difference (∆T) or the energy change (∆q)is
the multistage ignition process.
plotted on the ordinate and temperature or time is plotted on
critical half thickness, (a), n—an estimation of the half
the abscissa (see Figs. 3 and 4). E537
thicknessofasampleinan unstirred container,inwhichthe
dust concentration, n—the mass of dust divided by the
heatlossestotheenvironmentarelessthantheretainedheat.
internal volume of the test chamber. E1491
This buildup of internal temperature leads to a thermal-
runaway reaction. E1231
extrapolated onset temperature,n—empirically,thetempera-
critical temperature, (T ), n—an estimation of the lowest ture found by extrapolating the baseline (prior to the peak)
c
temperature of an unstirred container at which the heat andtheleadingsideofthepeaktotheirintersection(seeFig.
losses to the environment are less than the retained heat 3). E537
leading to a buildup of internal temperature. This tempera-
final temperature (T ), n—the lowest temperature, cor-
final
ture buildup leads to a thermal-runaway reaction. E1231
rected to a pressure of 101.3 kPa (760 mmHg, 1013 mbar),
DISCUSSION—This description assumes perfect heat removal at the
at which application of an ignition source causes the vapors
reaction boundary. This condition is not met if the reaction takes place
of the specimen to ignite under specified conditions of test.
in an insulated container such as when several containers are stacked
together or when a container is boxed for shipment. These figures-of- E1232
merit underestimate the hazard as a result of this underestimation of
flash point, n—the observed system temperature at the end of
thermal conductivity.
an exotherm, generally at the temperature where the self-
deflagration index, (K ), n—maximum dP/dtnormalizedtoa
St
heat rate of the reaction has decreased below the operator-
1.0 m volume. It is measured at the optimum dust concen-
defined slope sensitivity threshold. (1981) E1232
tration. K is defined according to the following cubic
St
n
general rate law—dC/dt= k(1− C) where C is fractional
relationship:
conversion, t is the time in minutes, and n is the reaction
1/3
K 5 ~dP/dt! V
St
max
order. E698
where:
guide bushing,n—thesteelbushingthatsurrounds,aligns,and
P = pressure, (bar),
holds the stationary intermediate weight in place. E680
E1445 − 08 (2015)
guide system, n—therails
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E1445 − 08 (Reapproved 2015)
Standard Terminology Relating to
Hazard Potential of Chemicals
This standard is issued under the fixed designation E1445; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E698 Test Method for Arrhenius Kinetic Constants for
Thermally Unstable Materials Using Differential Scan-
1.1 This standard is a compilation of terminology used in
ning Calorimetry and the Flynn/Wall/Ozawa Method
the area of hazard potential of chemicals. Terms that are
E771 Test Method for Spontaneous Heating Tendency of
generally understood or adequately defined in other readily
Materials (Withdrawn 2001)
available sources are not included.
E918 Practice for Determining Limits of Flammability of
1.2 Although some of these definitions are general in nature,
Chemicals at Elevated Temperature and Pressure
many must be used in the context of the standards in which
E1226 Test Method for Explosibility of Dust Clouds
they appear. The pertinent standard number is given in paren-
E1231 Practice for Calculation of Hazard Potential Figures-
theses after the definition.
of-Merit for Thermally Unstable Materials
1.3 In the interest of common understanding and
E1232 Test Method for Temperature Limit of Flammability
standardization, consistent word usage is encouraged to help
of Chemicals
eliminate the major barrier to effective technical communica-
E1491 Test Method for Minimum Autoignition Temperature
tion.
of Dust Clouds
E1515 Test Method for Minimum Explosible Concentration
2. Referenced Documents
of Combustible Dusts
E1981 Guide for Assessing Thermal Stability of Materials
2.1 ASTM Standards:
by Methods of Accelerating Rate Calorimetry
E476 Test Method for Thermal Instability of Confined Con-
E2012 Guide for the Preparation of a Binary Chemical
densed Phase Systems (Confinement Test) (Withdrawn
Compatibility Chart
2008)
E2019 Test Method for Minimum Ignition Energy of a Dust
E487 Test Method for Constant-Temperature Stability of
Cloud in Air
Chemical Materials
E2021 Test Method for Hot-Surface Ignition Temperature of
E537 Test Method for The Thermal Stability of Chemicals
Dust Layers
by Differential Scanning Calorimetry
E2046 Test Method for Reaction Induction Time by Thermal
E582 Test Method for Minimum Ignition Energy and
Analysis
Quenching Distance in Gaseous Mixtures
E659 Test Method for Autoignition Temperature of Liquid
3. Terminology
Chemicals
E680 Test Method for Drop Weight Impact Sensitivity of
3.1 Definitions:
Solid-Phase Hazardous Materials
adiabatic calorimeter, n—an instrument capable of making
E681 Test Method for Concentration Limits of Flammability
calorimetric measurements while maintaining a minimal
of Chemicals (Vapors and Gases)
heat loss or gain between the sample and its environment,
which is verifiable by the capability to continuously measure
the temperature differential between the sample and its
This terminology is under the jurisdiction of ASTM Committee E27 on Hazard
surroundings. E1981
Potential of Chemicals and is the direct responsibility of Subcommittee E27.01 on
Editorial and Nomenclature.
adiabatic decomposition temperature rise, (T) , n—an esti-
d
Current edition approved Feb. 1, 2015. Published April 2015. Originally
mation of the computed temperature which a specimen
approved in 1991. Last previous edition approved in 2008 as E1445 – 08. DOI:
would attain if all of the enthalpy (heat) of decomposition
10.1520/E1445-08R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
reaction were to be absorbed by the sample itself. High
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
values represent high hazard potential. E1231
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 anvil, n—the smooth, hardened surface upon which the test
The last approved version of this historical standard is referenced on
www.astm.org. sample or cup containing the sample rests. E680
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1445 − 08 (2015)
−E/RT
Arrhenius equation—k = Ze where k is the specific
t = time, (s),
reaction rate constant in reciprocal minutes for first order, Z
V = volume, (m ), and
is the pre-exponential factor in reciprocal minutes, E is the K = (bar m/s).
St
Arrhenius activation energy in J/mol, R is the gas constant,
E1226
8.32 J/mol K, and T is the temperature in kelvin. E698
differential scanning calorimetry (DSC), n—a technique in
autoignition, n—the ignition of a material commonly in air as
which the difference in energy inputs into a substance and a
the result of heat liberation due to an exothermic oxidation
reference material is measured as a function of temperature,
reaction in the absence of an external ignition source such as
while the substance and the reference material are subjected
a spark or flame. E659
to a controlled temperature program. E698
DISCUSSION—Two modes, power compensation differential scanning
autoignition temperature, n—the minimum temperature at
calorimetry (power compensation DSC) and heatflux differential scan-
which autoignition occurs under the specified conditions of
ning calorimetry (heatflux DSC), can be distinguished depending on the
test. E659
method of measurement used.
DISCUSSION—Autoignition temperature is also referred to as sponta-
differential thermal analysis (DTA), n—a technique in which
neous ignition temperature, self-ignition temperature, autogenous igni-
tion temperature, and by the acronyms AIT and SIT. AIT is the lowest the temperature difference between a substance and refer-
temperature at which the substance will produce hot-flame ignition in
ence material is measured as a function of temperature while
air at atmospheric pressure without the aid of an external energy source
the substance and the reference material are subjected to a
such as spark or flame. It is the lowest temperature to which a
controlled temperature program. E698
combustible mixture must be raised, so that the rate of heat evolved by
the exothermic oxidation reaction will over-balance the rate at which
(dP/dt) , n—the maximum rate of pressure rise during the
ex
heat is lost to the surroundings and cause ignition.
course of a single deflagration. E1226
compatibility, adj—the ability of materials to exist in contact
(dP/dt) , n—maximum value for the rate of pressure in-
max
without specified (usually hazardous) consequences under a
crease per unit time reached during the course of a defla-
defined scenario. E2012
gration for the optimum concentration of the dust tested. It is
determined by a series of tests over a large range of
constant-temperature stability (CTS) value, n—the maxi-
concentrations. It is reported in bar/s. E1226
mum temperature at which a chemical compound or mixture
may be held for a 2-h period under the conditions of the test
drop weight, n—that weight which is raised to a selected
without exhibiting a measurable exothermic reaction. E487
height and released. This weight does not impact the sample
directly; rather it strikes another stationary weight that is in
cool-flame, n—a faint, pale blue luminescence or flame occur-
ring below the autoignition temperature (AIT). E659 contact with the sample. E680
DISCUSSION—Cool-flames occur in rich vapor-air mixtures of most
DTA (DSC) curve, n—a record of a thermal analysis where the
hydrocarbons and oxygenated hydrocarbons. They are the first part of
temperature difference (ΔT) or the energy change (Δq) is
the multistage ignition process.
plotted on the ordinate and temperature or time is plotted on
critical half thickness, (a), n—an estimation of the half
the abscissa (see Figs. 3 and 4). E537
thickness of a sample in an unstirred container, in which the
dust concentration, n—the mass of dust divided by the
heat losses to the environment are less than the retained heat.
internal volume of the test chamber. E1491
This buildup of internal temperature leads to a thermal-
runaway reaction. E1231
extrapolated onset temperature, n—empirically, the tempera-
critical temperature, (T ), n—an estimation of the lowest ture found by extrapolating the baseline (prior to the peak)
c
temperature of an unstirred container at which the heat and the leading side of the peak to their intersection (see Fig.
losses to the environment are less than the retained heat 3). E537
leading to a buildup of internal temperature. This tempera-
final temperature (T ), n—the lowest temperature, cor-
final
ture buildup leads to a thermal-runaway reaction. E1231
rected to a pressure of 101.3 kPa (760 mm Hg, 1013 mbar),
DISCUSSION—This description assumes perfect heat removal at the
at which application of an ignition source causes the vapors
reaction boundary. This condition is not met if the reaction takes place
of the specimen to ignite under specified conditions of test.
in an insulated container such as when several containers are stacked
together or when a container is boxed for shipment. These figures-of- E1232
merit underestimate the hazard as a result of this underestimation of
flash point, n—the observed system temperature at the end of
thermal conductivity.
an exotherm, generally at the temperature where the self-
deflagration index, (K ), n—maximum dP/dt normalized to a
St
heat rate of the reaction has decreased below the operator-
1.0 m volume. It is measured at the optimum dust concen-
defined slope sensitivity threshold. (1981) E1232
tration. K is defined according to the following cubic
St
n
general rate law—dC/dt = k(1 − C) where C is fractional
relationship:
conversion, t is the time in minutes, and n is the reaction
1/3
K 5 dP/dt V
~ !
St
max
order. E698
where:
guide bushing, n—the steel bushing that surrounds, aligns, and
P = pressure, (bar),
holds the stationary intermediate weight in place. E680
E1445 − 08 (2015)
guide system, n—the rails, wires, and shaft that guide the drop to ignite and propagate a flame away from the ignition
wei
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1445 − 08 E1445 − 08 (Reapproved 2015)
Standard Terminology Relating to
Hazard Potential of Chemicals
This standard is issued under the fixed designation E1445; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This standard is a compilation of terminology used in the area of hazard potential of chemicals. Terms that are generally
understood or adequately defined in other readily available sources are not included.
1.2 Although some of these definitions are general in nature, many must be used in the context of the standards in which they
appear. The pertinent standard number is given in parentheses after the definition.
1.3 In the interest of common understanding and standardization, consistent word usage is encouraged to help eliminate the
major barrier to effective technical communication.
2. Referenced Documents
2.1 ASTM Standards:
E476 Test Method for Thermal Instability of Confined Condensed Phase Systems (Confinement Test) (Withdrawn 2008)
E487 Test Method for Constant-Temperature Stability of Chemical Materials
E537 Test Method for The Thermal Stability of Chemicals by Differential Scanning Calorimetry
E582 Test Method for Minimum Ignition Energy and Quenching Distance in Gaseous Mixtures
E659 Test Method for Autoignition Temperature of Liquid Chemicals
E680 Test Method for Drop Weight Impact Sensitivity of Solid-Phase Hazardous Materials
E681 Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
E698 Test Method for Arrhenius Kinetic Constants for Thermally Unstable Materials Using Differential Scanning Calorimetry
and the Flynn/Wall/Ozawa Method
E771 Test Method for Spontaneous Heating Tendency of Materials (Withdrawn 2001)
E918 Practice for Determining Limits of Flammability of Chemicals at Elevated Temperature and Pressure
E1226 Test Method for Explosibility of Dust Clouds
E1231 Practice for Calculation of Hazard Potential Figures-of-Merit for Thermally Unstable Materials
E1232 Test Method for Temperature Limit of Flammability of Chemicals
E1491 Test Method for Minimum Autoignition Temperature of Dust Clouds
E1515 Test Method for Minimum Explosible Concentration of Combustible Dusts
E1981 Guide for Assessing Thermal Stability of Materials by Methods of Accelerating Rate Calorimetry
E2012 Guide for the Preparation of a Binary Chemical Compatibility Chart
E2019 Test Method for Minimum Ignition Energy of a Dust Cloud in Air
E2021 Test Method for Hot-Surface Ignition Temperature of Dust Layers
E2046 Test Method for Reaction Induction Time by Thermal Analysis
3. Terminology
3.1 Definitions:
adiabatic calorimeter, n—an instrument capable of making calorimetric measurements while maintaining a minimal heat loss or
gain between the sample and its environment, which is verifiable by the capability to continuously measure the temperature
differential between the sample and its surroundings. (E1981)
This terminology is under the jurisdiction of ASTM Committee E27 on Hazard Potential of Chemicals and is the direct responsibility of Subcommittee E27.01 on
Editorial and Nomenclature.
Current edition approved May 15, 2008Feb. 1, 2015. Published July 2008April 2015. Originally approved in 1991. Last previous edition approved in 20032008 as
E1445 – 03.E1445 – 08. DOI: 10.1520/E1445-08.10.1520/E1445-08R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1445 − 08 (2015)
adiabatic decomposition temperature rise, (T) , n—an estimation of the computed temperature which a specimen would attain
d
if all of the enthalpy (heat) of decomposition reaction were to be absorbed by the sample itself. High values represent high hazard
potential. (E1231)
anvil, n—the smooth, hardened surface upon which the test sample or cup containing the sample rests. (E680)
−E/RT
Arrhenius equation—k = Ze where k is the specific reaction rate constant in reciprocal minutes for first order, Z is the
pre-exponential factor in reciprocal minutes, E is the Arrhenius activation energy in J/mol, R is the gas constant, 8.32 J/mol K,
and T is the temperature in kelvin. (E698)
autoignition, n—the ignition of a material commonly in air as the result of heat liberation due to an exothermic oxidation reaction
in the absence of an external ignition source such as a spark or flame. (E659)
autoignition temperature, n—the minimum temperature at which autoignition occurs under the specified conditions of test.
(E659)
DISCUSSION—
Autoignition temperature is also referred to as spontaneous ignition temperature, self-ignition temperature, autogenous ignition temperature, and by
the acronyms AIT and SIT. AIT is the lowest temperature at which the substance will produce hot-flame ignition in air at atmospheric pressure without
the aid of an external energy source such as spark or flame. It is the lowest temperature to which a combustible mixture must be raised, so that the
rate of heat evolved by the exothermic oxidation reaction will over-balance the rate at which heat is lost to the surroundings and cause ignition.
compatibility, adj—the ability of materials to exist in contact without specified (usually hazardous) consequences under a defined
scenario. (E2012)
constant-temperature stability (CTS) value, n—the maximum temperature at which a chemical compound or mixture may be
held for a 2-h period under the conditions of the test without exhibiting a measurable exothermic reaction. (E487)
cool-flame, n—a faint, pale blue luminescence or flame occurring below the autoignition temperature (AIT). (E659)
DISCUSSION—
Cool-flames occur in rich vapor-air mixtures of most hydrocarbons and oxygenated hydrocarbons. They are the first part of the multistage ignition
process.
critical half thickness, (a), n—an estimation of the half thickness of a sample in an unstirred container, in which the heat losses
to the environment are less than the retained heat. This buildup of internal temperature leads to a thermal-runaway reaction.
(E1231)
critical temperature, (T ), n—an estimation of the lowest temperature of an unstirred container at which the heat losses to the
c
environment are less than the retained heat leading to a buildup of internal temperature. This temperature buildup leads to a
thermal-runaway reaction. (E1231)
DISCUSSION—
This description assumes perfect heat removal at the reaction boundary. This condition is not met if the reaction takes place in an insulated container
such as when several containers are stacked together or when a container is boxed for shipment. These figures-of-merit underestimate the hazard as
a result of this underestimation of thermal conductivity.
deflagration index, (K ), n—maximum dP/dt normalized to a 1.0 m volume. It is measured at the optimum dust concentration.
St
K is defined according to the following cubic relationship:
St
1/3
K 5 dP/dt V
~ !
St
max
where:
P = pressure, (bar)
t = time, (s)
V = volume, (m )
K = (bar m/s)
St
P = pressure, (bar),
t = time, (s),
V = volume, (m ), and
E1445 − 08 (2015)
K = (bar m/s).
St
(E1226)
differential scanning calorimetry (DSC), n—a technique in which the difference in energy inputs into a substance and a reference
material is measured as a function of temperature, while the substance and the reference material are subjected to a controlled
temperature program. (E698)
DISCUSSION—
Two modes, power compensation differential scanning calorimetry (power compensation DSC) and heatflux differential scanning calorimetry (heatflux
DSC), can be distinguished depending on the method of measurement used.
differential thermal analysis (DTA), n—a technique in which the temperature difference between a substance and reference
material is measured as a function of temperature while the substance and the reference material are subjected to a controlled
temperature program. (E698)
(dP/dt) , n—the maximum rate of pressure rise during the course of a single deflagration. (E1226)
ex
(dP/dt) , n—maximum value for the rate of pressure increase per unit time reached during the course of a deflagration for the
max
optimum concentration of the dust tested. It is determined by a series of tests over a large range of concentrations. It is reported
in bar/s. (E1226)
drop weight, n—that weight which is raised to a selected height and released. This weight does not impact the sample directly;
rather it strikes another stationary weight that is in contact with the sample. (E680)
DTA (DSC) curve, n—a record of a thermal analysis where the temperature difference (ΔT) or the energy change (Δq) is plotted
on the ordinate and temperature or time is plotted on the abscissa (see Figs. 3 and 4). (E537)
dust concentration, n—the mass of dust divided by the internal volume of the test chamber. (E1491)
extrapolated onset temperature, n—empirically, the temperature found by extrapolating the baseline (prior to the peak) and the
leading side of the peak to their intersection (see Fig. 3). (E537)
final temperature (T ) , ), n—the lowest temperature, corrected to a pressure of 101.3 kPa (760 mm Hg, 1013 mbar), at which
final
application of an ignition source causes the vapors of the specimen to ignite under specified conditions of test. (E1232)
flash point , point, n—the observed system temperature at the end of an exotherm, generally at the temperature where the self-heat
rate of the reaction has decreased below the operator-defined slope sensitivity threshold. (1981) (E1232)
n
general rate law—dC/dt = k(1 − C) where C is fractional conversion, t is the time in minutes, and n is the reaction order. (E698)
guide bushing, n—the steel bushing that surrounds, aligns, and holds the stationary intermediate weight in place. (E680)
guide system, n—the rai
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